Suitable Hydraulic systems

[TeamKnightshade]

Hello all!

I am finally embarking on my trip into heavyweight land, and would like to include a hydraulic system for a lifter. I chose hydraulic over electric simply because of the huge power you can achieve, and that nothing is strained if you stall the ram like an electric actuator would, so I believe it would be much more reliable.

I would appreciate some advice on the types of systems that are used by roboteers, especially on how leaks are prevented when the robot is inverted. I have seen some promising hydraulic power packs from flowfit (such as this: https://www.flowfitonline.com/hydrau...-tank-zz004236 ) but I am convinced that this tank would leak like a sieve through the breather if it was flipped! I have heard that some teams use an accumulator bladder as a tank, but I haven't seen many details on that.

Any details on what tank and valve setups other bots use would be greatly appreciated.

Cheers,

Jon

P.S. Before anyone says that the inexperienced should leave hydraulics alone, I have assembled and used hydraulic equipment at college and work. I am aware of the dangers and am happy to take my time and learn before proceeding

[team death]

Hi Jon
The main problem with hydraulics is they are slow and from experience with my heavyweight Robots

you can find yourself flipped a dozen times in the first minute by full pressure flippers or take a couple

of hits from a spinner without a retort from a slow moving weapon.

I'm all for new ideas with Robots but it might not be a round winner without a rapid and destructive

weapon.

[Team Helix]

Without being allowed accumulators hydraulics are hard to use effectively.

[Al_]

Hi Jon, I've used hydraulics in my featherweights for a while now, so they can be made to work. As Colin says they can be slow, but you have so much power there for a lifter, you could use a linkage to speed it up.
The biggest problem with those sorts of power packs as you have identifiec is the leak potential from the breather when it is inverted. To get around that I have used a bladder for the tank then given it some sort of secondary protection to stop it being punctured. However you need to be careful that when the amount of fluid in the tank is at it's greatest that the tank does not become pressurised so that you do not fall foul of the no accumulator rule. You also need to ensure there is no air in the tank as you do not want to end up in a situation where your pump is trying to suck air in and it stops working as a result.

[TeamKnightshade]

Thanks all for the advice!

To get around that I have used a bladder for the tank then given it some sort of secondary protection to stop it being punctured.

Alan, I see from your great build diary of pressure point that you used a Micro Reversible Powerpack from interfluid. I'm thinking that this would be a much better option for me as it removes all the need for the solenoid valves and stuff. Did you put the bladder inside the silver cover on your pump?

I'm thinking that if I size the ram appropriately and get the leverage right I could make a reasonably fast lifter that will still lift a ton with the relatively small pump. If this was a heavyweight crusher I was making I would definitely be using a bigger pump!

[Al_]

That build diary is a couple of robots out of date now, but I'm still using the same powerpack. I did start with a bladder inside the silver tank, but the prolem is you can inspect it to check it is OK. I moved on to a seperate and much thicker bladder without the silver tank.
You could probably use the powerpack for your lifter, but you are limited on flow rate on a pump that small, so it would all depend on the size of your ram and the linkage as you say.

[TeamKnightshade]

Thanks Alan, very helpful stuff!

[I'll Play One Day]

I'm a Linde forktruck technician and we use an airtight tank in our machines with 1 bar of positive pressure inside it to keep the dirt out. Obviously the 1 bar of pressure is maintained by the valve block, but it could be done with other brands.